The present invention relates to the doping of silicon, particularly to the determination of proper silicon doping utilized in integrated circuit fabrication, and more particularly to silicon device structures for obtaining real-time feedback during integrated circuit fabrication relative to the doping operation.
A significant problem in the integrated circuit manufacturing industry is that of monitoring the results of each process step. The importance of real-time process monitoring for accurate decision-making during the fabrication sequence has given rise to an entire industry devoted to providing the equipment necessary to accomplish this task. Of all of the processing steps, one of the most critical is that of doping the silicon semiconductor. Of utmost importance during the doping process is to achieve uniformity of both junction depth and impurity dose both across the silicon wafer and from wafer to wafer. To monitor the uniformity of dopants in silicon, numerous diagnostic tools have been developed. However, none of these tools gives real-time feedback concerning the electrically active impurity dose and the junction depth. The present invention addresses this problem. Using newly designed test structures and a pulsed laser annealing technique, the invention enables the measurement, in real time, of the active impurity dose and junction depth of doped junctions formed by both ion implantation and gas immersion laser doping (GILD). Data obtained from the test structures can be utilized to determine dopant yield during the doping operation.